HAIR AND HYDROLYZED WHEAT PROTEINS 199 Figure 3. Root-end hair treated with fluorescein-labeled peptides overnight. Block top. Fluorescence throughout the hair, but higher concentrations at its periphery and a greater overall level of fluorescence compared with the 30-minute treatment shown in Figure 2. One therefore adduces that, even after overnight treatment, not all the potential sites of occupation for the peptides are occupied. The highest intensity of fluorescence occurred at the perimeter of the undamaged root-end hairs, indicating that water rinsing had not removed significant amounts of material. In all samples the fluorescent peptides were contained principally within the endocuticle and in the nuclear remnants and intermacrofibrillar matrix of the cortex (Figures 4, 6). The boundaries of the cortical cells were also highlighted. The limited resolution of the images did not enable us to define the precise location of the peptides at the cell boundaries. On the other hand, we believe they are more likely to be contained within the non-keratin peripheral intracellular envelope of each cortical cell than within the adjacent cortical cell membrane complex (5). The nuclear remnants of the cortex pre- sented strikingly high levels of fluorescence that highlighted their characteristic stellate shape wherever they occurred within the transverse fiber cross sections. Hairs not treated with the labeled peptides were completely free from fluorescence at the detected wave- length (518 nm). That low levels of fluorescence were found in the exocuticle and cortical macrofibrils of peptide-treated hairs attests to penetration even of these dense structures. The main sites of residence for the peptides in the hairs are consistent with these same structures also acting as the principal pathways for the diffusion of aqueous-borne materials into human hair (5). Despite their average molecular mass in excess of 1000 Da, the peptides are clearly capable of penetrating the full depth of the human hair shaft. The high concentrations found in the nuclear remnants of the cortex and in the endo- cuticle are probably brought about by ionic interaction between the anionic hydrolyzed

200 JOURNAL OF COSMETIC SCIENCE Figure 4. Permanently waved hair treated overnight with fluorescein-labeled peptides. Physical section. This high-magnification micrograph shows that the components containing the fluorescer are the endocu- ticle (EN), and nuclear remnants (NR), the intermacrofibrillar matrix (IM), and cell boundaries (CB) of the cortex. wheat proteins and basic proteins, notably effete nuclear proteins (histones), expected to be present within these structures (6). In most, but not all, hairs that had undergone chemical processing (bleaching, perma- nent waving, and relaxer treatments), a peripheral annulus was seen extending to a depth of approximately 15 pro, where fluorescence was at a lower intensity than at greater depths in the fibers (cf. Figure 5). In these regions the nuclear remnants were poorly defined. Such effects could have been caused in the water-rinsing step by easier removal of the wheat peptides from chemically treated hairs than from untreated hairs. Another possibility is that basic proteins, to which the wheat peptides normally attach, have been removed from the hairs during the chemical treatments. In the case of the bleached hairs, cysteic acid formed in the peripheral annulus could have shifted the isoionic point of the local proteins to a lower pH, thereby opposing ionic binding of the wheat peptides. In ethnic black hairs, subjected beforehand to relaxer treatments, there was some evi- dence that the cortical cells contained a network of stained intermacrofibrillar matrix that was more extensive than seen in the other hairs of Caucasian origin (compare Figures 4 and 6). This would be consistent with earlier electron microscope observations that the highly crimped hairs of ethnic blacks contain more cells of an ortho-cortical character than are found in the straighter hairs of other racial groups (7,8). More work of a quantitative nature would be required to reach a firm conclusion about this. In some cases transverse sections through a split end indicated a simple bifurcation involving fracture through the hair's major axial diameter, and in others as many as 18 separated fibrillar units were seen (cf. Figure 7). The fluorescently labeled peptides had